The science behind snow
By NOAA
How are snowflakes formed?
A snowflake begins to form when an extremely cold water droplet freezes onto a pollen or dust particle in the sky. This creates an ice crystal. As the ice crystal falls to the ground, water vapor freezes onto the primary crystal, building new crystals – the six arms of the snowflake.
That’s the short answer.
Thank you, Kae, for linking to this NOAA story. A simple, fascinating explanation.